CN111567648A - Method for improving yield of tea water-soluble substances and content of amino acids - Google Patents

Abstract

The invention discloses a method for improving the yield and the amino acid content of a tea water soluble substance, which takes black tea, green tea, Pu-erh ripe tea or Pu-erh raw tea as raw materials, extracts the raw materials for three times by adopting a water extraction method, and adds neutral protease during the third extraction so as to achieve the purpose of improving the yield and the amino acid content of the tea water soluble substance; the method finishes the extraction of water-soluble substances in the tea in the first two water extractions, adds neutral protease for water extraction in the third extraction, and then inactivates the neutral protease; after the three extracts are mixed, the content of free amino acid and the ratio of the water-soluble extract can be increased under the condition of keeping the main components of the tea aqueous extract, the original flavor of the tea is kept, and the tea aqueous extract is very beneficial to ensuring the taste of the extract and improving the yield and flavor substances.

Description

A kind of method for improving tea water-soluble matter yield and amino acid content

technical field

The invention belongs to the field of tea processing, and particularly relates to a method for increasing the yield of water-soluble tea extract while retaining the main components of the water extract during tea extraction.

Background technique

Tea is one of the most popular beverages in the world, consumed by more than 2/3 of the world's people; with the expansion of people's activities, in order to meet their demand for tea, instant tea is small in size and strong in packaging. Light weight, convenient drinking and other characteristics, meet the needs of the fast-paced modern life and widely enter people's lives.

Instant tea is a deep-processed product of tea, with a wide range of raw materials; its processing technology is mainly composed of extraction, concentration, drying and other parts, in which the process of tea extraction is the main factor affecting its output; extraction generally uses water as the solvent to extract the soluble in tea leaves. The extraction methods include boiling water extraction, percolation extraction, continuous extraction, etc. The concentration of the first two methods is only 1-5%, the latter can reach 15-20%, and the extraction rate is very low. Tea protein accounts for 15-30% of the dry weight of tea leaves, and a large amount of structural protein is insoluble in water. How to improve the yield of water-soluble tea extract and make full use of the protein is a very worthwhile problem to explore.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the present invention provides a method for improving the yield and amino acid content of water-soluble tea leaves. The method can improve the water-soluble tea extract quality under the premise of ensuring the main substances of the tea water extract and the original quality of the tea soup. The method of the present invention degrades the protein that cannot be extracted into free amino acids by adding neutral protease during the third water extraction, destroys the internal structure of the tea leaves, and fully extracts the water-soluble substances in the tea leaves. The purpose of improving the yield of water-soluble tea extract and its free amino acid content is achieved.

In order to realize the above-mentioned purpose of the present invention, the technical scheme of the present invention is as follows:

Select several main varieties of instant tea, that is, take black tea, green tea, cooked Pu'er tea or raw Pu'er tea as raw materials, use water extraction method to extract the raw materials, and extract in three times, and the material-to-liquid ratio of each extraction is g:mL. : 5～15; the first and second extractions are extracted at 55～65℃ for 1～2h, the filtrates are collected respectively, water-soluble neutral protease is added during the third extraction, and neutral protease is added to the third extraction solution The mass volume concentration in the tea is 0.002-0.005%, and the extraction is performed at 45-55 ° C for 1-2 hours, the unextracted protein in the tea is hydrolyzed into amino acids, and the water-soluble substances in the tea are fully released, so as to improve the water-soluble content of the tea. The purpose of yield and amino acid content; to determine the content of protein, free amino acids and tea polyphenols in the three extracts; to combine the three extracts, and to measure the quality after vacuum drying.

In the present invention, neutral protease is added during the third water extraction of the tea leaves, and the protease is inactivated by boiling treatment when the extraction is completed, and then the extracts are combined for drying without affecting the substances in the first two extracts.

The beneficial effects of the present invention are as follows:

According to the invention, four kinds of tea leaves (black tea, green tea, Pu'er raw tea and Pu'er cooked tea) are crushed and then extracted with water, and neutral protease is added in the third extraction, and the first two water extractions are basically completed. In the extraction of water-soluble substances in tea leaves, neutral protease is added for water extraction during the third extraction, which can increase the content of free amino acids and the ratio of water-soluble extracts while retaining the main components of the water extract of tea leaves. The original flavor of tea leaves is very beneficial to ensure the taste of the extract and improve the yield and flavor substances.

Description of drawings

Fig. 1 is the determination result of the soluble protein content in the three water extracts of several tea leaves;

Figure 2 shows the measurement results of free amino acids in the three-time water extracts of several tea leaves (without adding neutral protease for the third time);

Figure 3 shows the measurement results of free amino acids in the three-time water extracts of several tea leaves (with neutral protease added for the third time);

Figure 4 is the determination result of the content of tea polyphenols in the three-time water extracts of several tea leaves (without adding neutral protease for the third time);

Fig. 5 is the determination result of the content of tea polyphenols in the three water extracts of several tea leaves (the third time adding neutral protease);

Figure 6 is the determination result of dry matter in the total mass of tea leaves in the three-time water extracts of several tea leaves (without adding neutral protease for the third time);

Figure 7 is the comparison result of the dry matter in the total mass of tea leaves in the three water extraction solutions of several tea leaves (without and with neutral protease added during the third extraction).

Detailed ways

The present invention will be described in further detail below through the examples and accompanying drawings, but the protection scope of the present invention is not limited to the content; the methods in the examples are carried out according to conventional operations unless otherwise specified, and the reagents used are conventional reagents unless otherwise specified. Or reagents prepared by conventional methods, unless otherwise specified, the percentages in the method are all mass percentages.

Embodiment 1: the method that this improves tea water-soluble yield and amino acid content is as follows:

Black tea, green tea, cooked Pu'er tea, and raw Pu'er tea were pulverized into small granules with a plant pulverizer. Take 1 g of each type of tea, add 10 mL of ultrapure water to each type of tea, and extract in a 60°C water bath for 1 hour. Filter and collect the filtrate; add 10 mL of ultrapure water to the filter residue, extract in a 60°C water bath for 1 h, filter, and collect the filtrate; add 10 mL of ultrapure water and neutral protease solution to the filter residue (the mass of neutral protease in the third extraction solution) The volume concentration is 0.005%), extracted in a 50 ℃ water bath for 1 h, filtered, and the filtrate was collected; at the same time, with no neutral protease added as a control, each of the above samples was tested three times; the filtrate was boiled for 10 min to inactivate the protease.

Example 2: Determination of the soluble protein content in the third extraction solution of Example 1

The protein content in the extraction solution of each step was determined by the BCA method; the protein content gradually decreased with the increase of extraction times, and the content of the third extraction solution was only about 10% of the total content of the first two extractions. The main soluble protein in tea has been extracted in this step, and the results are shown in Figure 1.

Example 3: Determination of the free amino acid content in the third extraction solution of Example 1

Ninhydrin colorimetric method was used to measure the content of free amino acids in the extract in each step, and the results are shown in Figures 2 and 3; the content of free amino acids showed a downward trend with the increase of extraction times, and no neutral protease was added. The content of free amino acids in the third extraction solution approached zero, and the content of free amino acids increased significantly after adding the enzyme.

Embodiment 3: measure the content of tea polyphenols in the third extraction solution of embodiment 1

The content of tea polyphenols in the extraction solution of each step was determined by the iron tartrate colorimetric method, and the results are shown in Figures 4 and 5; the content of tea polyphenols also showed a downward trend with the increase of extraction times. The content of tea polyphenols in the third extract had no significant effect.

Example 5: Determination of dry matter content in tea water extract

After the three extracts of each tea leaf without neutral protease were directly vacuum-dried, the content of dry matter in each step of the extract was measured. The results are shown in Figure 6, and the content of dry matter in the extract increased with the number of extractions. However, the content of dry matter in the third extraction solution of black tea and cooked tea is close to zero; the tea samples with neutral protease are dried in vacuum and the quality is determined. The total dry matter content in the extract is compared, and the comparison results are shown in Figure 7. The water-soluble extracts of black tea, green tea, Pu'er cooked tea and Pu'er raw tea were added with neutral protease during the third extraction. The content of dry matter increased by 38.8%, 9.5%, 41.5%, and 14.1%, respectively. The extraction rate of water soluble matter of black tea and Pu'er cooked tea increased significantly, and the extraction rate of water soluble matter of green tea and Pu'er raw tea also increased to a certain extent. Use a small spoon to take 0.2 g of the dried total extract with enzyme and the total extract without enzyme, put it in a glass, and brew it with 100 mL of boiling water. It is found that the soup is clear and clear, and there is no obvious difference in taste. It retains the flavor of the original tea leaves.

Example 6: Pulverize black tea, green tea, cooked Pu'er tea, and raw Pu'er tea into small granules with a plant pulverizer, take 1 g of each type of tea, add 15 mL of ultrapure water to each type of tea, and extract in a 55°C water bath for 2 hours. , filter with 8 layers of gauze, and collect the filtrate; add 15 mL of ultrapure water to the filter residue, extract in a water bath at 60°C for 1 h, filter, and collect the filtrate; add 15 mL of ultrapure water and neutral protease solution to the filter residue (neutral protease is extracted in the third extraction). The mass-volume concentration in the liquid was 0.002%), extracted in a 55°C water bath for 1 h, filtered, and the filtrate was collected; at the same time, with no neutral protease added as a control, each of the above samples was tested 3 times; the filtrate was boiled for 10 min to inactivate the protease ; The content of protein, free amino acids and tea polyphenols in the three extracts was determined, and the determination results were consistent with those in Example 1.

Claims (4)

1. A method for improving the yield of tea water-soluble substances and the content of amino acid is characterized by comprising the following steps: black tea, green tea, Pu 'er ripe tea or Pu' er raw tea are taken as raw materials, the raw materials are extracted for three times by a water extraction method, and neutral protease is added during the third extraction, so that the purposes of improving the yield of water-soluble substances of the tea and improving the content of amino acid are achieved.

2. The method for improving the yield and the amino acid content of the tea aqueous solution according to claim 1, wherein the method comprises the following steps: the first extraction and the second extraction are carried out for 1 to 2 hours at the temperature of 55 to 65 ℃.

3. The method for improving the yield and the amino acid content of the tea aqueous solution according to claim 1, wherein the method comprises the following steps: the third extraction is carried out at 45-55 ℃ for 1-2 h, and the mass volume concentration of the neutral protease in the third extraction solution is 0.002-0.005%.

4. The method for improving the yield and the amino acid content of the tea aqueous solution according to claim 1, wherein the method comprises the following steps: the ratio of the feed liquid to the water extract is 1: 5-15 g/mL.

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